甲酯化方法对甘油三酯和游离型脂肪酸混合物脂肪酸分析的影响

Comparison of Methyl Esterification Methods in Fatty Acids Determination of the Mixture Composed of Triglycerides and Free Fatty Acids

在重组解脂耶氏酵母催化红花籽油合成共轭亚油酸的过程中,大量的红花籽油与游离型亚油酸及共轭亚油酸以混合物的形式存在于发酵液上清。为了通过气相色谱准确分析催化过程中底物及产物的含量,确定甘油三酯和游离型脂肪酸混合物的最佳甲酯化方法至关重要。本试验选择盐酸-甲醇法、盐酸-甲醇(甲苯)法、三氟化硼-甲醇法、氢氧化钠-甲醇法、酸碱综合法和重氮甲烷法6种方法,对红花籽油、游离型共轭亚油酸和二者混合物分别进行甲酯化,通过气相色谱定量分析,比较甲酯化效率。结果表明盐酸-甲醇(甲苯)法甲酯化程度高,且操作简便、安全、经济,是样品为甘油三酯和游离型脂肪酸混合物的最适甲酯化方法。

During the conjugated linoleic acid （CLA） synthesised by recombinant Yarrowia lipolytica, catalytic safflower seed oil, plentiful safflower seed oil, free - floating type linoleic acid （LA） and conjugated linoleic acid were existed in the form of mixture in fermented supernatant. In order to analyze the content of substrate and outcome in the catalytic process by gas chromatography accurately, it was crucial to determine the best methyl esterification methodof mixtures of triglycerides and free fatty acids. In this study, six different methods including hydrochloric acid - methanol method, hydrochloric acid - methanol （ add methylbenzene ） method, BF3 - methanol method, NaOH -methanol method, acid -base synthetic method, diazomethane method were selected to carry out methyl es- terification for the safflower seed oil and free -floating type conjugated linoleic acid and their mixtures respectively, by chromatogram ration analysis and then compare efficiency of methyl esterification. The results obtained showed that hydrochloric- methanol （add methylbenzene） method was the optimal methyl esterification method for the mixture sample composed of triglycerides and free fatty acids, due to the high methyl esterification efficiency, user - friendly control and low toxicity and cost.